The present invention relates to an air in-line sensor for use in a medical device and, more particularly, to an air in-line sensor designed to detect air bubbles in a therapeutic solution flowing through a tube.
An infusion system for delivering a drug or other liquid into a patient often includes an infusion device that operates to deliver the liquid at an adjustable rate or dosage. Prior art infusion devices include an air detector using an ultrasonic or an optical sensor for detecting air bubbles in the liquid flowing through a tube. The air detector is loaded in a part of the tube.
Two types of the air detectors are known. More specifically, in the separate type as shown in FIG. 1, a signal emitting member 1 and a signal receiving member 2 of the detector are separate components in such a structure. The signal emitting member 1 is mounted on a stationary unit 3 of a pumping station, while the signal receiving member 2 is carried by a movable unit 4, such as a door. When the door 4 is closed, a channel 5 is defined between an upper surface of signal emitting member 1 of stationary unit 3 and a lower surface of signal receiving member 2 of movable unit 4, into which a tube 6 is accommodated. Accordingly, when movable unit 4 is closed while tube 6 is loaded into an upper recess 7 defined in signal emitting member 1 of stationary unit 3, tube 6 is deformed into a flattened configuration within channel 6 to provide an enlarged surface area in contact with signal emitting and receiving members 1 and 2. receiving members 1 and 2 are embedded in opposing walls of groove 8. The unitary type is mainly used for detecting relatively short air bubbles and therefore the length of tube-receiving groove 8 is relatively short, exerting less resistance in contact between the groove and the tube. Accordingly, the tube may be fitted into groove 8 by pushing with one""s fingers.
In the above-described separate type, it is difficult to maintain a constant, specific distance between the signal emitting and receiving members so as to stabilize the performance of the detector, because the separate type sensor system has more tolerances than a unitary type system. When more tolerances are involved, distance control between the signal emitting and receiving members becomes more difficult.
Nuisance alarms result when a pump alarm is activated when air is not present in the line. As a result, air sensors are often deactivated in the pump""s configuration. Accordingly, the pump would not be able to detect the presence of air in the line. Moreover, nondetection of actual air in the tubing line occurs in many prior art infusion devices because the ultrasonic signal is not fully transmitted through the tube. For example, an ultrasonic signal may work its way around the bottom of the channel and trick the pump mechanism into believing that liquid is in the line when, in fact, air is in the line. This nondetection or xe2x80x9cshort circuitxe2x80x9d is undesirable.
Some unitary type air sensors have included a pocket underneath the channel to block the ultrasonic signal, and thus, prevent the ultrasonic signal from circumventing the correct path through the tubing set. However, these pockets can allow dirt and cleaning solutions to build up, which prevents the sensor from working properly. If the pocket became filled with liquid, the ultrasonic signal may travel around the channel even when air is present in the tubing line.
Moreover, some unitary type air sensor systems do not maintain optimal contact between the tube and the channel. For example, if a flat closure member surface is utilized to push the tube into a V-shaped, upper section of the channel, the tube may become dislodged from the channel by rotational or rolling displacement of the tube. Additionally, the tube may flatten or collapse disproportionately, causing poor coupling between the tube and the channel.
U.S. Pat. No. 5,102,392, owned by Assignee of the present invention, discloses an air detector for use in infusion pumps (see FIGS. 2 and 3). The air detector utilizes a unitary type sensor for detecting air bubbles in the tube. The upper section of the groove has a first side wall which tapers upwardly and outwardly from the tube fixing section and a second side wall is perpendicular to the base of the groove along the length of the tube fixing section. When the door is closed after the tube is loaded in the groove, the tube abutting member forces the tube against the second side wall and into final position.
The present invention is provided to solve these and other problems.
The present invention provides an air in-line sensor for detecting air bubbles in a therapeutic solution flowing through a tube.
According to one aspect of the present invention, the sensor has a channel for receiving the tube having a tube loading section. The sensor further has a signal emitting member positioned on one side of the tube and a signal receiving member positioned on an opposite side of the tube. A first air baffle is positioned between the signal emitting member and the signal receiving member.
According to another aspect of the invention, the sensor has a first lead-in section defined by an upper portion of a first sidewall of the channel. The first lead-in section tapers upwardly and outwardly from an intermediate portion of the first sidewall to the upper portion of the first sidewall.
According to a further aspect of the invention, the sensor has a second lead-in section positioned opposite the first lead-in section. The second lead-in section is defined by an upper portion of a second sidewall of the channel, and the second lead-in section tapers upwardly and outwardly from an intermediate portion of the second sidewall to the upper portion of the second sidewall.
According to a further aspect of the invention, the sensor has a second air baffle positioned between the signal emitting and the signal receiving members.
According to yet another aspect of the invention, an air in-line sensor is provided for detecting air bubbles in a therapeutic solution flowing through a tube. The sensor has a channel for receiving the tube having a tube loading section. Preferably, the tube has a first lead-in section. The tube loader has a stationary section and a movable section hingedly connected to the stationary section. The movable section has a blade having a radius of curvature for positioning the tube in the tube loading section. Preferably, a signal emitting member is positioned on one side of the tube and a signal receiving member is positioned on an opposite side of the tube.
According to a further aspect of the invention, an air in-line sensor system is disclosed for detecting air bubbles in a therapeutic solution flowing through a tube located in a pumping mechanism. The tube extends from a supply bag of the therapeutic solution to a patient through the system. The system has a channel for receiving the tube having a first lead-in section, and a tube loading section. A signal emitting member is positioned on one side of the tube and a signal receiving member is positioned on an opposite side of the tube. A first air baffle is positioned between the signal emitting member and the signal receiving member. Moreover, the tube loader has a stationary section and a movable section hingedly connected to the stationary section. The movable section has a blade having a radius of curvature for positioning the tube in the tube loading section.
According to yet another aspect of the invention, a method is disclosed for loading a tube into a channel of a medical pump. Preferably, the channel is provided having a first lead-in section and a tube loading section. The channel is also provided having a signal emitting member positioned on one side of the tube and a signal receiving member positioned on an opposite side of the tube. A tube loader is provided having a stationary section and a movable section. The movable section has a blade having a radius of curvature. The tube is positioned proximate the channel. The blade is placed in contact with the tube, and the blade is then moved until the tube is positioned within the tube loading section.
Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.